1. Field of the Invention
The invention relates to a measuring device with signal generators with adjustable, stable and reproducible phases and frequencies and a method for the operation of a measuring device for generating signals with adjustable, stable and reproducible phases and frequencies.
2. Discussion of the Background
In metrology, for example, in network-analysis metrology, a high-frequency signal is used to supply the device under test. A further high-frequency signal is used as a local oscillator signal in order to mix the received generator signals into an appropriate intermediate frequency position. If a complex wave value, such as the wave reflected at the input of the device under test, is to be determined according to magnitude and phase via the frequency, the frequency and phase ratios of both high-frequency signals after each frequency step of the incrementally processed measurement-frequency range must be known. Otherwise only a ratio measurement, in which the absolute phase is irrelevant, can be carried out.
The problem becomes particularly significant if a plurality of signal generators is involved, for example, in the case of differential multi-port measurements, or complex conversion measurements on frequency-converting devices under test, for example, mixers. Several signals of different frequencies are then necessary. These are usually generated by means of independent signal generators. However, an exact frequency ratio and an exact phase ratio are then no longer provided.
One possibility for implementing complex conversion measurements is described by the “Secum-Trahenz Method” in the German published patent application DE 10 2006 003 839 A1.
According to this method, the signal generators and local oscillators are generated starting from one common reference signal. The reference signal is divided by fractional splitters. In this manner, any desired frequencies of the reference signal can be generated. However, the phase relationship is lost via the fractional splitting. The phase relationship is only restored via a phase correction. However, this is very slow and requires a large volume of software. Furthermore, a new correction of the phases of the signals is required after every change in frequency. This results in a slow measurement speed.